The invention relates to a heat exchanger, particularly a scraping heat exchanger having an outer cylinder comprising a first wall having a smooth circle-cylindrical inner side, and an inner cylinder positioned concentrically therewithin, comprising a second wall having a smooth circle-cylindrical outer side, wherein both sides together define a vertically arranged space for cooling and/or heating a liquid and/or viscous product.
The heat exchanger can be used for all kinds of purposes, such as for instance preparing jam. In that case it should be avoided as much as possible that the fruit breaks down into pieces. Other examples of products are mayonnaise, soft filling for cookies, dairy products, but also ink for printers.
Such a heat exchanger is described in Dutch patent Nr. 8701906. As the inner side and outer side are scraped the inner side and/or outer side are subject to wear, particularly when metal scrapers are used. Among others when the outer side of the inner cylinder is worn the heat exchanger can no longer be used. If replacing the inner cylinder is possible at all, it is a difficult and laborious job as this cylinder is hard to reach and often is welded to a flange at a lower side of the heat exchanger which substantially closes off the vertically arranged space at a lower side.
When treating pollution-sensitive materials, such as food products and/or medical products, there is also the risk of air or polluting particles from outside of the space end up in the heat exchanger in the space. This is particularly the case when a sealing between the space in the heat exchanger and the space outside of it shows defects.
A further drawback of the known heat exchanger is that product gets lost when the space is not sufficiently filled. In a known method, after ending the product supply, the product is discharged from the chamber at a lower side; the treatment of the product in the heat exchanger is not yet completed at that moment so that this part of the product is not suitable for further processing. This results in loss of product.
It is an object of the invention to at least partially solve at least one of the above-mentioned problems.